Many list web forms provoke an email confirmation to the subscriber's email address provided in the form but malicious entities are now using this feature to do bulk form submissions with forged addresses that flood the subscriber’s inbox. M3AAWG members collaborated across the industry to propose a header as an initial step that hosting and sending companies can implement to help protect against these attacks. The header allows receivers to identify floods of mail coming from sign-up forms that are bombarding victim mailboxes.